Resin-made components are frequently employed as components of vehicles, digital products, or the like, in place of metal materials in order to reduce weight and cost. Particularly in vehicle components, various sensors are mounted on the vehicles for a high-function controlling of an engine. Therefore, it is no exaggeration to say that quality of configuration of the resin-made components plays a part for reliability of the vehicle. Further, in digital household electric appliances, tiny resin-made members mechanically play important roles, with a tide of miniaturization and integration. In addition, precision components, made of glass and ceramics, also play important roles in the components of the vehicle and of the digital household appliances. Accordingly, it is important to quantitatively evaluate defects in configuration of such components.
Members made of high polymer materials such as resin material and rubbers, and inorganic materials such as glass and ceramics are manufactured by extrusion molding, injection molding, and by compressive burning, for example. However, the members manufactured may include a stepped portion, a blister, a projection, a roughness, or the like.
Conventionally, such defective portions are detected by irradiating an electromagnetic wave (terahertz wave) with wavelength to pass through an object and then examining a change of transparent intensity of the electromagnetic wave after transmitting through the object. For example, one of such defect detecting method and device is disclosed in Japanese Patent No. 2005-43230A (hereinafter, referred to as reference 1).
The above-described defect detecting device detects a defect of an elongated member (such as a pipe member) with uniform cross section on the basis of a change of transparent intensity of an electromagnetic wave passing through the elongated member. However, the transparent intensity of the electromagnetic wave is influenced by a defect inside of the object and compositional homogeneity of composition of the object, for example. Therefore, greater noise may be generated, and sensitivity and precision for defect detection may be lowered. Further, the transparent intensity is integrated in accordance with a direction where the electromagnetic wave is irradiated. Therefore, measurement of the defect from an irradiated direction may not be obtained. Still further, according to the known method and device, existence or nonexistence of the defect at the uniform cross section of the elongated member is qualitatively evaluated. However, the defect of an object without a pipe-shaped configuration may not be quantitatively evaluated. Accordingly, size and shape as three-dimensional configuration of the defect may not be quantitatively evaluated.
A need thus exists for a method and a device for configuration examination which are not susceptible to the drawback mentioned above.